The present invention relates to a gas turbine engine combustor having at least one trapped vortex cavity and, more particularly, to a liner for such combustor forming at least a portion of such trapped vortex cavity which is arcuate in a transition area between adjacent portions so as to relieve stress and possible deflection.
Advanced aircraft gas turbine engine technology requirements are driving the combustors therein to be shorter in length, have higher performance levels over wider operating ranges, and produce lower exhaust pollutant emission levels. One example of a combustor designed to achieve these objectives employs a trapped vortex cavity, as disclosed in U.S. Pat. Nos. 5,619,855 and 5,791,148 to Burrus. As seen therein, the Burrus combustor has inner and outer liners attached to the dome inlet module which include upstream cavity portions for creating a trapped vortex of fuel and air therein, as well as downstream portions extending to the turbine nozzle.
Further refinements to the combustor disclosed in the aforementioned patents are disclosed in U.S. Pat. Nos. 6,286,298 and 6,295,801 to Burrus et al., where a dome inlet module separate from the diffuser is described. It will be seen therefrom that a fuel injector bar is utilized to supply fuel to the openings between the vanes of the dome inlet module. In this way, a Rich-Quench-Lean (RQL) process is employed to achieve low emissions in the combustor. Additional improvements to the trapped vortex cavity (TVC) combustor have also been disclosed to increase cooling of the liners at indicated locations (U.S. Pat. No. 6,286,317 to Burrus et al.) and to alleviate interference between dome-to-liner joints and the fuel injectors (U.S. Pat. No. 6,334,298 to Aicholtz).
It has now been found that stress at a corner of the liners adjacent the rear walls is unsatisfactory and could lead to potential deflection or collapse of the rear liner wall. Further, flow characteristics in the cavity indicate that recirculation zones are formed in the same liner corners which create undesirable heat stress. In light of high temperature capability of such material, it is also contemplated that Ceramic Matrix Composite (CMC) be utilized for the liners of the TVC combustor. This has led to other concerns for the same corner location, as such material is currently limited in its processing for geometries involving minimal corner fillets.
Accordingly, it would be desirable for a liner to be developed for a trapped vortex cavity combustor which does not incur stress above an acceptable level. It is also desirable for the flow characteristics and cooling in a corner thereof be improved. Further, it would be desirable if such liner could be configured so as to enable use of Ceramic Matrix Composite therefor.